"Some people said that my rhetoric is very strong," he said during remarks at a joint news conference in Tokyo alongside Japanese Prime Minister Shinzo Abe. "But look at what's happened with very weak rhetoric over the last 25 years. Look where we are now."
Trump's comments came on his second day in the region, where Trump hopes to reaffirm his tough stance on North Korea and rally allies to endorse his strategy.
He achieved that with Abe, who said Monday that he "100%" agreed with Trump's strategy.
Abe said that Japan and the US are in "complete agreement" as to the way forward in dealing with North Korea, including that now is not the time for direct talks with North Korea.
"We were in complete agreement as to the measures to be taken on the situation with North Korea," Abe said, noting that he agrees "all options" should remain on the table.
The Japanese Prime Minister also said now is a time for a strengthening of sanctions against Pyongyang.
"For more than 20 some years, the international community attempted dialogue with North Korea," Abe said. "Now is the time not for dialogue but for applying a maximum level of pressure on North Korea."
Abe and Trump delivered the rhetoric emphasizing a tough strategy on North Korea after meeting moments earlier with the families of Japanese citizens kidnapped by the North Korean regime, and alluded to the death of American Otto Warmbier to bolster his case for an aggressive approach toward Pyongyang.
Trump encouraged North Korea's leader Kim Jong Un to release all hostages, saying it would send positive signals to the world.
But the two leaders also emphasized their resolve to deal with North Korea through the strength of sanctions and other pressure rather than through direct dialogue days after Trump said he would be willing to meet with any world leader, including dictators like Un.
"I would sit with anybody I feel. I don't think it's strength or weakness. I think sitting down with people is not a bad thing," he told "Full Measure" in an interview that aired Sunday
While it was not the first time Trump had signaled his openness to meeting with Un, he and his administration have continued maintain that while they aren't ready to close he door on talks, now is not the right time.